Researchers have demonstrated consistently that caffeinated alcohol (CA) use, or the mixture of alcohol (e.g., vodka) with a caffeinated beverage (e.g., Red Bull), is associated with a host of negative consequences. These problems include increased drug use (Brache & Stockwell, 2011; Snipes & Benotsch, 2013), risky sexual behaviors, risky driving behaviors, and heavy episodic drinking (O'Brien et al., 2008) beyond typical non-CA drinking behavior. Limited research has examined factors that underlie the relationship between CA use and alcohol-related problems. Further, existing research has been cross-sectional and based on retrospective reports of alcohol use, which have been called into question (Ekholm, 2004). Consequently, the proposed application seeks to address gaps in our understanding of CA use by conducting a daily diary study that would investigate CA use longitudinally and provide much needed information regarding the contextual and social factors that are associated with CA use. Aim 1 is designed to examine the context (e.g., location and social context of consumption) in which college students consume CA. Aim 2 is intended to extend previous research by investigating various negative consequences (e.g., risky driving, risky sexual behaviors, broad alcohol-related problems, caffeine-related physiological symptoms) related to daily CA use in a within-subjects design. Finally, because we have limited understanding of why emerging adults use CA, Aim 3 is designed to measure substance-related cognitions (e.g., alcohol expectancies, caffeine expectancies, drinking motives) associated with daily CA consumption, as these are strong predictors of alcohol use in general. Daily diary data would allow participants to provide reports close to the time CA use occurs. Further, a daily diary study would permit examinations of the relationships between cognitive and contextual factors and CA outcomes longitudinally along with the ability to examine how context and cognitions are associated with individual variability in CA use. Results from this research are intended to enhance our understanding of the antecedents and consequences related to CA use to develop strategies to address this public health concern. Ultimately, the findings from the proposed research could aid in targeting an intervention for CA users. Also, findings could be used to identify the types of users who would most benefit from secondary prevention. By determining the factors associated with one type of risky beverage and alcohol-related harms, the proposed study supports NIAAA's initiative of enhancing our understanding of the risks associated with consuming alcohol. This award also would allow me to obtain essential training in advanced methodology and statistical techniques, develop further alcohol expertise, work with additional alcohol researchers, prepare and disseminate findings to the larger research communities, and gain grant-writing skills. All of these activities will facilitate a research-orieted academic career focused on understanding problematic alcohol consumption.